1. Characteristics of chronic pyelonephritis The incidence of chronic pyelonephritis in women is 2-5%; chronic pyelonephritis in patients with primary renal and urinary tract disease leads to severe renal failure (vesicoureteral reflux, narcotic drug abuse, kidney stones, or obstruction) in 13%-26%; patients without primary renal and urinary tract disease rarely develop chronic pyelonephritis, and it is rare for chronic pyelonephritis to lead to renal failure. The risk of renal failure is rare. 2. Clinical symptoms of chronic pyelonephritis Intermittent fever, lumbago and urinary symptoms may occur in patients with extended acute pyelonephritis. Primary patients are mostly asymptomatic and gradually progress to renal insufficiency. Laboratory tests for chronic pyelonephritis: characteristic tests of UTI such as bacteriuria and pyuria do not mean chronic infection of the kidney, and most patients have normal urine tests due to urinary tract obstruction and other reasons. Imaging tests: intravenous pyelogram with irregular kidney shape, dilated or blunted individual calyces, and renal scar formation at the corresponding calyces. 4, treatment principles The most important thing about chronic pyelonephritis lies in the early detection, because early detection may be divided into two kinds, the first is whether the patients with acute pyelonephritis is prolonged into chronic pyelonephritis, so the treatment of acute pyelonephritis must be sufficient, early active detection. The second is to keep the urinary tract open for patients with primary kidney disease and upper urinary tract structures with abnormalities who gradually develop renal insufficiency. Monitoring and protecting kidney function and reducing kidney damage is the only way to achieve the goal of treating pyelonephritis. If bacteria are found in the urine by various examination modalities, antibiotics with low kidney damage and high concentration in the urine can be applied for a long period of 4 to 6 weeks or more. Bacterial “relapse” in chronic pyelonephritis is due to incomplete initial treatment; comorbidities; and retention of foreign bodies in the upper urinary tract that are not conducive to bacterial clearance.